The present invention is related to an automatically controlled ventilation system for providing a forced air exchange in the dead air spaces of a structure. Although such dead air spaces can exist in a variety of areas, the present system is particularly suited for use in the crawl space beneath a house or other structure where the building foundation raises the sub-floor above the ground.
Lack of sufficient ventilation and movement of air in such crawl spaces results in a build-up of excess moisture and also a build-up of Radon gases. Failure to dissipate such build-up leads to undesirable conditions such as pest problems, fungal growth, sweating and resultant damage to floor trusses and other structural components. Further, the humidity can invade the interior areas of the house, causing structural damage and/or growth of fungi or molds in the house. Heating and air conditioning loads are also increased by excess humidity levels.
Previous approaches to the control or elimination of such problems have been primarily related to installation of foundation ventilators, some of which open or close responsive to the temperature of outside air. Other approaches include the application of layers of polymeric materials over the earth within the crawl space. However, these materials do not inhibit the spread of moisture within the underlying dirt, and do not eliminate the problem. These layers of polymeric materials generally only delay humidity damage. Further, there is no effect on moisture which enters through open ventilators.
Regarding specific ventilator problems, most foundation-type ventilators are of the wire screen or mesh type and are closed either by the placing of a solid shield over the face of the ventilator, or by a shutter hingedly connected to the rear of the vent screen and pulled closed by means of a rod which extends outwardly from the shutter. Such structure is prone to failure because the screens puncture, the shutters fail to close, or do not close tightly, as a few examples only.
The present invention eliminates the above problems by provision of a unique forced air ventilation system and an improved ventilator. The air flow system itself includes an intake unit and an exhaust unit. The ventilator structure is of an improved sliding-plate-type having a solenoid control for opening and closing the sliding plate.
The intake unit of the ventilation system includes an intake ventilator positioned at a selected location in the foundation, and a temperature sensing device for sensing the temperature of the outside air. For example, it is undesirable to have the ventilator open when outside air is at sub-freezing levels because the admission of sub-freezing air can cause pipes to freeze and also increase the load on the furnace or other heating system. In the present system, when air temperature drops below freezing, the thermostatic control activates the solenoid to close the vent(s).
The exhaust unit also includes at least one solenoid-operated ventilator, a fan, and a humidity-sensing device. The humidistat is set to a predetermined humidity level and positioned in the area subject to the greatest humidity. When the humidity in this area rises above the prescribed level, the humidistat closes an electrical circuit, sending power to the thermostat. If, however, the outside temperature is below freezing, the thermostat will have relayed the signal, closing down the system, and the exhaust fans will not operate. Both the thermostat and the humidistat can be set to any desired level according to prevailing climatic needs. As stated above, the primary function of the thermostat is to prevent the introduction of sub-freezing air into the structural foundation. Thus, if the outside temperature is above freezing when the humidistat relays a signal to the thermostat, the thermostat will close the circuit and send power to the solenoid and the exhaust fan.
One advantage found is that the present invention permits the reduction of the number of ventilators necessary in a foundation wall because of the moving air. Therefore, there is less opportunity for cold air and moisture to enter the crawl space.
It was therefore an object of the present invention to provide an automatic system for ventilating the dead air spaces within a structure. It was a further objective to provide a ventilation system for crawl spaces, which system would function automatically, responsive both to humidity levels within the crawl space and to outside temperature.
Other and further objects will become apparent as the following detailed description is studied in conjunction with the following drawings.